Energy-Efficient Lighting: Lumens vs. Watts

As the Federal Trade Commission (FTC) and lighting manufacturers place more information on light bulb packaging, it’s important to learn the difference between watts (the old way of labeling bulbs) and lumens (the new way).

 What's a Watt?

Watts measure the amount of power a bulb uses – not how bright it is. So, using watts to describe brightness is like using gallons of fuel to describe how fast a car can go.This practice wasn't a problem as long as we continued to use the more than 100-year-old incandescent bulbs.

The problem: Traditional incandescent light bulbs waste 90% of their electricity to produce heat, and use only 10% to produce light. The solution: energy-efficient bulbs, which use fewer watts to give off the same amount of brightness.

As more consumers buy energy-efficient bulbs, labels on bulb packages are using a more accurate measurement of brightness: lumens.

Look for Lumens

Lumens measure the amount of light produced by a bulb. The more lumens in a light bulb, the brighter the light

The FTC’s conversion chart shows how lumen measurements match up to the old wattage amounts (see image on the right).

For example:

  • 40-watt incandescent bulb = 450 lumens
  • 60-watt incandescent bulb = 800 lumens
  • 100-watt incandescent bulb = 1600 lumens

More on Lumens vs. Watts

  • FTC video: How to look for lumens when buying bulbs

New Labeling Tips